ok, you could have kept it miles to keep things simple. But basically you did the cirumference (78,225miles) divided by two, which is 39112.5miles (then you converted to Km) correct? Which is a faster way of taking the diameter (24900miles) and dividing it by 2 (geting 12450miles - which is the diameter of the circle made by the equator if on a flat earth) and then multiplying by Pi (to get 39112.5miles).
So heres the RE measurments:
Earth's Circumference at the Equator: 24,901.55 miles (40,075.16 km)
Earth's Circumference Between the North and South Poles: 24,859.82 miles (40,008 km)
Notice that 39112.5miles does not = 24901 miles
So yeah, they stole the RE measurment for the earths circumference and thought well, if the earth was actually flat, then the circumference of what they think is a sphere, is actually the measurment for the diameter of our flat earth. (then they used it to make their ficticous flat earth circumference, which doesnt disagree with a RE measurment, because we dont have one in our spherical world lol)
Here they made 2 errors, first they stole the measurment for the circumference at the equator instead of the one that goes through the poles (lol - someone didnt try too hard with their steal here, the RE isnt a perfect sphere). Their second error, is that they stole a RE measurment. Because if they take this one measurent, it means they are approving of the RE measurment for the diameter of their flat earth, but they for no reason at all reject their other measurments (to keep it simple we will just talk about that of the equator).
I mean fair enough if you claim that all the RE measurments are wrong, and you need to prove this somehow and give us your measurments, because our ones seem to work pretty fine for, well everything like gps, flights, car trips across europe, whatever. the circumference of your earth is bigger then ours, this not only fucks up the measurments for the equator, but for the northeren and southern hemispheres.
In conclusion, without actually looking at the shape of the earth, you can simply mathmatically deduce the shape of the earth by measuring a couple of its dimesions. You cant claim these measurments are just a made up conspirisy because these measurements are used every day by hundreds of thousands of people.